Motor drive

ABSTRACT

An apparatus for driving a motor that opens and closes the window of vehicle, for example, is so adapted that when the vehicle becomes submersed in the sea, a lake or a river, etc., the window is prevented from being closed owing to malfunctioning of a relay caused when a leakage current flows into an operating switch for opening and closing the window. When submersion is sensed and it is sensed that the motor is being rotated by a malfunction in a direction that closes the window, a relay for rotating the motor in the forward direction is actuated. This prevents the occurrence of a situation in which the motor is caused to rotate (especially in the direction that closes the window) regardless of the fact that the operating switch has not been operated.

TECHNICAL FIELD

This invention relates to a motor drive apparatus, e.g., the driveapparatus of a motor for opening and closing the power window of avehicle.

BACKGROUND ART

A mechanism (power window) for opening and closing a window by thedriving force of a motor is employed in many vehicles. Though one suchmechanism which controls the forward and reverse rotation of the motor(the opening and closing of the window) directly by an operating switchis available, a variety of electronically controlled power windowsystems have recently come into widespread use. For example, onemechanism is such that if a foreign object of some kind becomes caughtbetween the window frame and the window glass when the window is beingclosed, this is sensed and control is carried out to reverse therotation of the motor and open the window. Another such mechanismremotely controls the opening and closing of the window by wirelesscommunication.

In any case, many systems use relays to drive the window opening andclosing motor in the forward and reverse directions and to halt therotation thereof. Consequently, if an accident occurs in which thevehicle falls into the sea or into a river and sinks, the motor may beactuated, owing to malfunction of the relays, regardless of the factthat neither operation of the switch nor electronic control is carriedout. For example, if the motor rotates in the reverse direction and thewindow closes, the driver and any passengers will become trapped insidethe vehicle.

A motor drive apparatus using relays for the power window of a vehicleaccording to the prior art will be described with reference to FIG. 6a.

The window of a vehicle is opened and closed by the rotation of a motor1. There are provided a relay 2 for rotating the motor 1 in the forwarddirection (to open, i.e., lower, the window), and a relay 3 for rotatingthe motor 1 in the reverse direction (to close, i.e., raise, thewindow).

The relay 2 includes a relay coil 2 a and relay contacts 2 b. The relaycontacts 2 b include a normally open contact (make contact or a contact)NO and a normally closed contact (break contact or b contact) NC. Therelay 3 includes a relay coil 3 a and relay contacts 3 b. The relaycontacts 3 b includes a normally open contact NO and a normally closedcontact NC.

The contacts (or terminals) NO of these relay contacts 2 b, 3 b areconnected to the line of a power supply E1, and the contacts (orterminals) NC of these relay contacts are connected to ground. Commonterminals C of these relay contacts 2 b, 3 b are connected to positiveand negative terminals ma, mb, respectively, of the motor 1. The motorrotates forward when a positive voltage is applied to the terminal maand in reverse when a positive voltage is applied to the terminal mb.

The relay coil 2 a of relay 2 is connected between the line of a powersupply E2 and ground and in series with a window-opening operatingswitch 4. Similarly, the relay coil 3 a of relay 3 is connected betweenthe line of the power supply E2 and ground and in series with awindow-closing operating switch 5.

The two operating switches 4, 5 are illustrated as being separatelyprovided as operating switches. In actuality, however, the switches 4and 5 usually are equipped with a common operating knob capable of beingrocked back and forth. The structure used is such that the switch 4 isturned on when the knob is swung in one direction and the switch 5 isturned on when the knob is swung in the other direction.

Single-pole, double-throw contacts (transfer contacts or break-makecontacts) are illustrated as the relay contacts 2 b, 3 b. It goeswithout saying, however, that the apparatus may have parallel-connectednormally open contacts NO and normally closed contacts NC, as shown inFIG. 6b.

If the operating switch 4 is turned on, the relay coil 2 a is energizedto actuate the relay contacts 2 b. The common terminal C in the relaycontacts 2 b is connected to the normally open contact NO and separatesfrom the normally closed contact NC. Accordingly, current flows from theline of power supply E1 to the positive terminal ma of motor 1 throughthe normally open contact NO and common terminal C of the relay contacts2 b, and current that flows out of the negative terminal mb of motor 1flows to ground through the common terminal C and normally closedcontact NC of relay contacts 3 b. As a result, the motor 1 rotates inthe forward direction and the window is opened. When the operatingswitch 5 is turned on, current from the power supply E1 flows to groundthrough the contacts 3 b, motor 1 and contacts 2 b, so that the motor 1rotates in the reverse direction and the window is closed.

The above-described motor drive apparatus is such that energization ofthe relay coils 2 a, 3 a is controlled directly by turning the operatingswitches 4, 5 on and off. There is also an apparatus of the type inwhich the states of operating switches are judged by a single-chipmicrocomputer or the like and the energization of the relay coils iscontrolled based upon the judgment made.

FIG. 7 illustrates an example of a conventional motor drive circuit thatrelies upon such control by microcomputer. A controller (circuit) 13typified by a microcomputer is provided in the diagram of FIG. 7. Anoperating switch 14 has a common terminal C and two normally opencontacts NO1, NO2. Under ordinary conditions, the common terminal C isnot connected to either the contact NO1 or the contact NO2. The commonterminal C is connected to ground. A power-supply voltage E3 is appliedon the contacts NO1, NO2 via pull-up resistors 15, 16, respectively.Under ordinary conditions, these voltages are applied to correspondinginput ports of controller 13.

In comparison with the circuits of FIGS. 6a and 6 b, the circuit of FIG.7 has relay control transistors 11, 12 instead of the operating switches4, 5 connected in series with the relay coils 2 a, 3 a, respectively.The control terminals 11, 12 are on/off controlled by the controller 13.Under ordinary conditions, these transistors 11, 12 are held in the offstate.

If an operating knob is moved or swung in one direction so that thecontact NO1 of operating switch 14 is connected to the common terminalC, the contact NO1 is brought to ground level. The ground-level voltageis sensed by the controller 13. The controller 13 outputs a controlsignal (H level) that turns on the transistor 11, and the relay coil 2 ais energized to rotate the motor 1 in the forward direction. If theoperating knob is swung in the other direction, the contact NO2 ofoperating switch 14 is connected to the common terminal C. Thecontroller 13 senses the ground level at the contact NO2 and outputs acontrol signal that turns on the transistor 12, as a result of which therelay coil 3 a is energized to rotate the motor 1 in the reversedirection.

The above-described motor drive apparatuses are such that if the vehiclefalls into the sea, a lake or a river and the apparatus becomessubmersed, there is a possibility that a phenomenon (so-called leakage)will occur in which, depending upon the quality of the water, a currentflows into either contact of the operating switches (switches 4, 5 orswitch 14) despite the fact that the operating knob has not beenoperated. As a consequence, there is the possibility that problems willarise, such as the motor 1 being rotated in the forward or reversedirection, the reversely rotating motor being stopped or control overthe motor being lost, regardless of the fact that the operating knob hasnot been operated.

In general, a relay has a hysteresis characteristic, in which thevoltage for actuating the relay (the voltage, which shall be referred toas the “actuating voltage”, applied to a relay coil in order to turn ona normally open contact or turn off a normally closed contact) is higherthan the voltage (which shall be referred to as the “restorationvoltage”) for returning the relay to the ordinary state. That is, if avoltage that exceeds the actuating voltage is applied to the relay coil,the relay is actuated; when the applied voltage falls below therestoration voltage, the relay returns to the original state. Further,there is a variation in the actuating voltage or restoration voltagefrom one relay to another. In other words, even if relays of the sametype are used, the actuating voltage and restoration voltage thereofdiffer slightly depending upon the individual relay.

Undesirable phenomena that can occur if a vehicle (strictly speaking,the portion of the motor drive apparatus in which the relays orswitches, etc., are placed) is submersed will be described keeping theabove-mentioned facts in mind.

If leakage develops across the ends of operating switch 4 or 5 in FIG.6a, this is equivalent to a resistor (referred to as a “leakageresistor”) being connected in parallel with the operating switch. Such asituation is illustrated in FIG. 8. Here an operating switch SW is theoperating switch 4 or 5, and a relay coil CL is the relay coil 2 a or 3a. The power-supply voltage is represented by the character E, and aleakage resistor is represented by the characters RL. Since leakagecurrent flows through the resistor RL, a coil voltage VCL is producedacross the relay coil CL. The coil voltage VCL changes in dependenceupon the state of submersion (impurities contained in the water) andbecomes extremely unstable.

If the coil voltage VCL resulting from leakage is higher than theactuating voltage of the relay, a phenomenon occurs in which the relayis actuated to rotate the motor despite the fact that the operatingswitch has not been operated. For example, if the actuating voltage ofthe relay 2 for opening the window is higher than the actuating voltageof the relay 3 for closing the window and the coil voltage VCL due toleakage is between the actuating voltages of the two relays 2, 3, thenonly relay 3 will be actuated and the window will close. If the windowcloses, this will impede the escape of passengers from the submersedvehicle.

In a case where the coil voltage VCL due to leakage is higher than theactuating voltages of both the relays 2 and 3, both of the relays 2 and3 are actuated. Since the normally open contacts NO in the relaycontacts 2 b, 3 b of the relays 2, 3 are both turned on, thepower-supply voltage E1 is impressed across the motor 1 and the motor 1does not rotate. Even if the operating switch 4 or 5 is turned on underthese conditions, the motor 1 will not rotate. Thus the operatingswitches have absolutely no effect.

If the coil voltage VCL due leakage declines and falls below therestoration voltage of either of the relays 2, 3 under these conditions,this relay is restored. Since the other relay is not restored andremains actuated, the motor 1 rotates in the forward or reversedirection. For example, if the restoration voltage of relay 2 is higherthan the restoration voltage of relay 3, only relay 2 is restored andthe motor 1 rotates in the reverse direction, as a result of which thewindow is closed.

Further, if a submersion accident occurs and the coil voltage VCL due toleakage surpasses the restoration voltage of the relay 3 when one of theoperating switches, e.g., the operating switch 5, has been turned on bythe driver or by a passenger to close the window, the relay 3 continuesto operate so as to close the window even if the operating switch 5 isturned off.

These undesirably phenomena can occur in the circuit of FIG. 7 as well.The operating switch 14 develops leakage owing to submersion, a currentflows to ground through the resistor 15 and contact NO1, and a currentflows to ground through the resistor 16 and contact NO2. The voltagesthat appear at the contacts NO1 and NO2 are sensed by the controller 13.If the controller 13 recognizes that the voltage at contact NO1 or NO2or the voltages at both of these contacts is/are less than a thresholdvoltage level, the controller outputs a control signal that turns on thetransistor 11 or 12 or both of these transistors. As a result, the motor1 rotates in the forward direction or reverse direction or a state isattained in which the motor cannot be controlled by the operating switch14.

Though it is considered that the foregoing problems will be solved byadopting a waterproof structure for the operating switches, this is noteasy to accomplish in actual practice. The reason is that it isdifficult technically to adopt a waterproof structure solely for theswitch contacts while maintaining the operating knob of the operatingswitches in a rockable state and exposing a portion of the knob. Even ifachieving this is feasible, an increase in cost results.

DISCLOSURE OF THE INVENTION

An object of the present invention is to prevent the occurrence of asituation in which the motor operates against the will of the operatorowing to relay malfunction caused by submersion in water.

Another object of the present invention is to so arrange it that a motoris made to operate in accordance with the will of the operator even if asubmersion accident occurs.

A motor drive apparatus according to the present invention has a relaymainly for operating to rotate a motor in a forward direction, and arelay mainly for operating to rotate a motor in a reverse direction. Amotor forward-rotation command or reverse-rotation command is applied byan operator through an operating portion (operating knob, operatingswitch, etc.). The forward-rotation relay or reverse-rotation relay isactuated in response to the forward-rotation command or reverse-rotationcommand (e.g., directly in response to the operating switch being turnedon or off, or through a microprocessor or other control circuit),thereby causing the motor to rotate in the forward or reverse direction.

In accordance with the present invention, the motor drive apparatus hassubmersion sensing means for sensing that at least an operating portionof the motor drive apparatus has become submersed; first malfunctionsensing means for sensing that one relay of the above-mentioned relays,which is for rotating the motor in a predetermined one direction, hasbeen actuated; and first forcible control means for actuating the otherrelay in response to submersion being sensed by the submersion sensingmeans and actuation of the one relay being sensed by the firstmalfunction sensing means.

If submersion is sensed and actuation of the one relay is sensed, thenthe other relay also is actuated by the first forcible control means.Since the relay for forward rotation of the motor and the relay forreverse rotation of the motor are both actuated, the motor ultimatelyassumes a state in which in will not rotate in either the forward orreverse direction (e.g., a state in which the same potentials appear atboth ends of the motor). This makes it possible to prevent theoccurrence of a situation in which the motor rotates in one directionagainst the will of the operator owing to malfunction of one relaycaused by submersion.

A pair of the malfunction sensing means and a pair of the forciblecontrol means may be provided. Specifically, the motor drive apparatusaccording to the present invention further includes second malfunctionsensing means for sensing that the other relay has been actuated, andsecond forcible control means for actuating the one relay in response tosubmersion being sensed by the submersion sensing means and actuation ofthe other relay being sensed by the second malfunction sensing means.

This makes it possible to prevent the occurrence of a situation in whichthe motor rotates in the other direction owing to malfunction of theother relay caused by submersion.

The submersion sensing means and malfunction sensing means can also beimplemented by a single means, as will be described later.

In a preferred embodiment of the present invention, there is provided ashorting circuit for establishing a short circuit across a relay coil ofthe relay that rotates the motor in the one direction, in operativeassociation with manipulation of the operating portion so as to generatea command that rotates the motor in the other direction.

By virtue of the shorting circuit, the ends of one malfunctioning relayare shorted, as a result of which this relay is restored to the ordinarystate. Accordingly, when the operator applies a command that actuatesthe other relay, only this other relay is actuated (or has already beenactuated by the forcible control means) and the motor runs in accordancewith the will of operator.

The present invention can also be expressed in the followed manner:Specifically, the present invention provides a motor drive apparatushaving two relays for rotating a motor in a forward or reverse directionby supplying power to the motor, wherein the relays are actuated torotate the motor in the forward or reverse direction in accordance withthe operating state of an operating portion that is for commandingforward or reverse rotation of the motor, characterized by havingsubmersion malfunction sensing means for outputting a submersionmalfunction detection signal upon sensing that the motor drive apparatushas become submersed and that one relay of the above-mentioned relays,which is for rotating the motor in one direction, has been actuated; andforcible control means for energizing a relay coil that is for actuatingthe other of the above-mentioned relays, irrespective of the operatingstate of the operating portion, in response to output of the submersionmalfunction detection signal.

The submersion malfunction sensing means outputs the submersionmalfunction detection signal upon sensing that the motor drive apparatushas become submersed and that one relay, which is for rotating the motorin one direction, has been actuated. If the submersion malfunctiondetection signal is output, the forcible control means energizes a relaycoil in order to actuate the other relay regardless of the operatingstate of the operating portion.

If a relay malfunctions owing to leakage brought about by submersion,the submersion malfunction detection signal is output and the otherrelay also is actuated by being energized by the forcible control means.Both relays ultimately are actuated, therefore, to establish a state inwhich the motor cannot rotate in either direction. Accordingly, it ispossible to prevent, with a high degree of reliability, the occurrenceof a situation in which the motor rotates in either direction againstthe will of the operator owing to malfunction of only one of the relayscaused by leakage resulting from submersion.

The present invention can be expressed all-inclusively as follows:Specifically, the present invention provides a motor drive apparatushaving two relays for rotating a motor in a forward or reverse directionby supplying power to the motor, wherein the relays are actuated torotate the motor in the forward or reverse direction in accordance withthe operating state of an operating portion that is for commandingforward or reverse rotation of the motor, characterized by havingsubmersion sensing means for outputting a submersion detection signalupon sensing that the motor drive apparatus has become submersed; andforcible control means for actuating both of the relays, irrespective ofthe operating state of the operating portion, in response to output ofthe submersion detection signal.

The submersion sensing means outputs the submersion detection signalupon sensing that the motor drive apparatus has become submersed. If thesubmersion detection signal is output, the forcible control meansenergizes both of the relay coils regardless of the operating state ofthe operating portion. If a submersion accident occurs, therefore, thesubmersion detection signal is output, both relays are actuated byforcible control exercises by the forcible control means and the endresult is that a state in which the motor cannot rotate in eitherdirection is established. Accordingly, it is possible to prevent, with ahigh degree of reliability, the occurrence of a situation in which themotor rotates in either direction owing to actuation of only one of therelays caused by leakage resulting from submersion.

In an embodiment, the motor is a motor for driving an opening andclosing body of a vehicle. By applying the motor drive apparatus of thepresent invention to a motor that drives an opening and closing body (apower window or sunroof, etc.) of a vehicle, a malfunction in which theopening and closing body is actuated against the will of a passenger isprevented even in the event of an accident in which the vehicle becomessubmersed.

According to another embodiment, rotation of the motor in one directionis rotation in a direction that closes the opening and closing body, androtation of the motor in the other direction is rotation in a directionthat opens the opening and closing body.

In the case of the direction in which a relay coil forcibly actuated bythe forcible control means opens the opening and closing body of thevehicle, a malfunction especially in a direction in which the openingand closing body of the vehicle is closed is prevented. This makes itpossible to maintain the opening and closing body in the open statereliably even in a case where a vehicle submersion accident hasoccurred. This enables the passengers to escape from the passengercompartment easily, thereby enhancing the safety of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of a motor drive apparatus according to afirst embodiment;

FIG. 2 is a circuit diagram of a motor drive apparatus according to asecond embodiment;

FIG. 3 is a circuit diagram illustrating a modification of the secondembodiment;

FIG. 4 is a circuit diagram of a motor drive apparatus according to athird embodiment;

FIG. 5 is a circuit diagram illustrating a modification of the thirdembodiment;

FIGS. 6a and 6 b and FIG. 7 are circuit diagram illustrating a motordrive apparatus according to the prior art; and

FIG. 8 is a circuit diagram illustrating the reason why a relaymalfunction occurs owing to generation of leakage caused by submersion.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 illustrates a first embodiment of the present invention.Components identical with those shown in FIG. 6a and in FIG. 7 aredesignated by like reference characters and are not described again.

The above-described operating switch 4 and relay control transistor 11are connected in parallel and so are the operating switch 5 and therelay control transistor 12. The transistors 11, 12 are on/offcontrolled by a controller 21.

The controller 21, which includes a microprocessor, for example,controls the automatic opening and closing of a power window, performscontrol to prevent an object from becoming caught in the power windowand controls remote operation of the power window in accordance with aninternal program.

An overview of automatic open/close control is as follows: the operatingswitch 4 or 5 is turned on in accordance with operation of the operatingknob. A switch or contact (not shown) turns on in operative associationwith the operating switch 4 or 5. The fact that this switch or contacthas been turned on is sensed by the controller 21. The latter turns onthe transistor 11 or 12 based upon detection of the ON state.Accordingly, even if the operating switch 4 or 5 is turned offsubsequently, the relay coil 2 a or 3 a continues to be energized andthe motor 1 continues rotating (in the forward or reverse direction).The transistor 11 or 12 is held in the ON state until the window isopened or closed completely. The completely open or closed state of thewindow is sensed by a sensor or on the basis of the load (current orvoltage) on the motor 1.

Control for preventing an object from becoming caught in the window isexecuted when the motor 1 is rotating in the reverse direction to closethe window. When the motor 1 is being rotated in the reverse direction,the power-supply voltage E1 is impressed upon the terminal mb of themotor 1 and the terminal ma is at the ground level. Since these voltagesat respective ends of the motor 1 are applied to the controller 21 viainput ports (terminals) 25, 24, the controller 21 is capable of sensingthat the motor 1 is at rest, rotating in the forward direction orrotating in the reverse direction. The fact that a foreign object ispresent between the window frame and the window glass (the fact that theobject has become caught) is sensed based upon the rotating speed of themotor, the load (overload) on the motor, etc. If a caught object issensed when the motor 1 is being rotated in the reverse direction, thecontroller 21 holds the transistor 12 in the OFF state and turns on thetransistor 11. The relay 2, therefore, is actuated. If the operatingswitch 5 is turned off, the motor 1 is rotated in the forward direction.The controller 21 rotates the motor 1 forward a predetermined amount tothereby open the window a predetermined amount. When the operatingswitch 5 is in the ON state, the power-supply voltage E1 is impressedacross the motor 1 and, hence, the motor 1 stops rotating.

An overview of control for remote operation is as follows: The apparatusis provided with a device (not shown) for receiving radio waves (orinfrared radiation) from a remote controller. When a window open orclose command is being transmitted from the remote controller, thecontroller 21 turns on the transistor 11 or 12 in accordance with thiscommand, thereby opening or closing the window.

The control unit (circuit or device) 20 includes the above-mentionedcontroller 21, control transistors 11, 12, a transistor 22 for sensingsubmersion and reverse rotation of the motor, and a transistor 23 forforcibly driving (rotating) the motor. The control unit 20, which is onetype of hybrid IC, is provided with a waterproof structure by moldingthe controller 21 and transistors 11, 12, 22, 23 in plastic. The controlunit 20 has the terminals 24, 25 connected to the ends ma, mb of motor1, terminals 26, 27 for connecting the transistors 11, 12 in parallelwith the operating switches 4, 5, and an open terminal 28 for sensingsubmersion. The open terminal 28 is exposed to the exterior of themolded surface. The open terminal 28 is provided at a location at whichthere is high likelihood that the terminal will be submersed atapproximately the same time as the operating switches 4, 5. A lead wiremay be laid from the terminal 28 to the vicinity of the operatingswitches 4, 5, in which case it is preferred that at least the tip ofthe lead wire be exposed (i.e., that the covering be removed from thetip).

The emitter of the transistor 22 is connected to the input terminal 25,the collector is connected to the base of the transistor 23 and the baseis connected to the open terminal 28. The transistor 23 is connected inparallel with the transistor 11 (in parallel with the operating switch 4via the terminal 26).

If the motor drive apparatus is submersed, so is the open terminal 28. Astate is thus attained in which the open terminal 28 is connected toground via the resistance component (leakage resistance) in water. Whenthe motor 1 is rotating in the reverse direction, the power-supplyvoltage E1 is being applied to the terminal mb of the motor. The voltageE1 thus is being applied to the emitter of the transistor 22 through theterminal 25. Since the base of transistor 22 is connected to ground viathe open terminal 28, the transistor 22 turns on. The transistor 22performs two functions, namely sensing of reverse rotation of motor 1and sensing of submersion.

If the transistor 22 is turned on, the base of transistor 23 attains theH level (a potential approximately equal to the power-supply voltage E1)and, hence, the transistor 23 turns on. The relay 2 is actuated as aresult. The transistor 23 is for forcibly actuating the relay 2, whichis for forward rotation of the motor (for forcibly driving the motor 1in the forward direction).

Since the motor 1 was being rotated in the reverse direction byactuating the relay 3, the power-supply voltage E1 is being applied tothe terminal mb of the motor 1, as set forth above. Since the relay 2 isforcibly actuated by detection of submersion under these conditions, thenormally open contact NO of relay contact 2 b and the common terminal Care connected. As a result, the power-supply voltage E1 is applied tothe terminal ma of motor 1. The motor 1 stops rotating because bothterminals ma and mb of the motor 1 take on the same potential. Thus, ifsubmersion is sensed when the motor 1 is rotating in the reversedirection, the motor 1 ceases being driven.

According to this embodiment, a circuit is also provided to forciblyhalting actuation of the relay 3 (if this relay is being actuated),which is for rotating the motor 1 in the reverse direction so as toclose the window (the result of this operation being that the motor isrotated in the forward direction). This circuit is for the purpose ofproducing a short circuit across both ends of the relay coil 3 a ofrelay 3 and includes a switch 31 and a shorting line 32. The switch 31,which is one type of changeover switch, has a common terminal Cconnected to one side (the power-supply side) of relay coil 3 a, anormally closed terminal NC connected to the power supply E2, and anormally open contact NO connected to the other side (the ground side)of the relay coil 3 a via the line 32. The switch 31 operates inassociation with the switch 4 that commands forward rotation of themotor 1. When the switch 4 is turned on, the switch 31 is changed overso as to connect the common terminal C to the normally open contact NO.

If the switch 4 is turned on by operating the operating knob in order toopen the window, therefore, the ends of the relay coil 3 a are shortedby the switch 31 and line 32. Accordingly, energization of the relaycoil 3 a ceases and the relay 3 (relay contact 3 b) is restored to theordinary state as a result. The motor 1 is rotated in the forwarddirection, to thereby open the window, by the forced actuation of relay2 (by transistor 23 being turned on) in response to sensing ofsubmersion or by actuation of relay 2 in response to the operatingswitch 4 being turned on.

Even if leakage caused by submersion occurs between the common terminalC and normally closed contact NC of the switch 31, the leakage currentflows through the shorting line 32, the resistance of which is less thanthat of the relay coil 3 a. As a consequence, almost no current flowsinto the relay coil 3 a and the relay 3 is not actuated.

The danger that passengers of a vehicle will become trapped inside thevehicle arises when a relay malfunction caused by submersion is of thekind where the motor 1 is driven reversely in the direction in which thewindow closes. According to this embodiment, the relay 2 for rotatingthe motor 1 in the forward direction is forcibly actuated when a certaincondition, i.e., detection of submersion and reverse rotation of themotor 1, is established. As a result, the power-supply voltage E1 isimpressed across the terminals ma, mb of motor 1 and the motor 1 isstopped immediately. This prevents the occurrence of a highly dangeroussituation in which the window moves in the closing direction owing tocoil voltage produced by leakage that accompanies submersion.

Further, when the operating knob is operated in a direction to open thewindow (i.e., when switch 4 is turned on), the ends of the relay coil 3a for reverse rotation are shorted by the switch 31, which operates inassociation with the switch 4, and the shorting line 32. As a result,the relay contacts 3 b are restored to the ordinary state. Because therelay 2 is actuated by turn-on of switch 4 (or because the relay 2 hasbeen forcibly actuated based upon detection of submersion), the motor 1is rotated in the forward direction and the window is opened. Even ifthe relay 3 for reverse rotation has been actuated owing to leakage, therelay 3 is restored and the window can be opened with assurance.

The motor 1 can be utilized to open and close not only a window but alsovarious opening and closing bodies such as a sunroof.

Thus, in accordance with this embodiment, a malfunction in which anopening and closing body moves in a closing direction owing to asubmersion accident can be prevented and a motor can be driven in thedirection that opens the opening and closing body in response tomanipulation of an operating switch.

According to this embodiment, there are merely provided the twotransistors 22, 23 and the open terminal 28. The structure is thereforesimple and the apparatus can be reduced in size and lowered in cost.

The controller 21 and transistors 11, 12 are for controlling theautomatic opening and closing of a power window, performing control toprevent an object from becoming caught in the power window andcontrolling remote operation of the power window, as set forth above.Since these components are not necessarily required to preventmalfunction caused by a submersion accident, they can be omitted.

The inventors have performed submersion experiments using a motor driveapparatus having the circuitry shown in FIG. 1 and have confirmed thatthen drive apparatus operates in the manner described above.

FIG. 2 illustrates a second embodiment. Components in FIG. 2 identicalwith those shown in FIG. 1 are designated by like reference charactersand are not described again.

The first embodiment prevents a malfunction in which the motor isrotated in a direction that closes the window owing to a coil voltageproduced by leakage. The second embodiment, however, prevents not only amalfunction in which the motor is rotated (reversely) in a directionthat closes the window but also a malfunction in which the motor isrotated (forwardly) in a direction that opens the window. To accomplishthis, a control unit 40 is additionally provided with a transistor 42,which is for detecting submersion and forward rotation of the motor andis controlled by the potential at the open terminal 28, having itsemitter connected to the terminal 24 to which the voltage at theterminal ma of the motor 1 is applied; and a transistor 43, which is forforcibly actuating a relay for reverse rotation of the motor, controlledby the transistor 42 and is connected in parallel with the reply controltransistor 12.

As a result of submersion, the base of the transistor 42 issubstantially grounded via the open terminal 28. If it is assumed thatthe power-supply voltage E1 was being applied to the terminal ma ofmotor 1 at this time (i.e., that the motor was being rotated in theforward direction), the transistor 42 will turn on. Since the transistor43 also turns on as a result, a current flows into the relay coil 3 aand the normally open contact NO of the relay contacts 3 b is turned on.The potentials at both ends of the motor 1 therefore take on equalvalues E1 and the motor 1 stops.

In FIG. 2, a single transistor can perform the roles of both transistors11 and 23, and the transistors 12 and 43 can be replaced by a singletransistor. A circuit in which the number of transistors is thus reducedis illustrated in FIG. 3.

The base of the common transistor 11 in a control unit 50 is connectedto the controller 21 and to the collector of the transistor 22 viareverse-current diodes 51, 52, respectively. Similarly, the base of thecommon transistor 12 is connected to the controller 21 and to thecollector of the transistor 42 via reverse-current diodes 53, 54,respectively.

FIG. 4 illustrates a third embodiment.

Like the controller 13 shown in FIG. 7, a controller 61 controls therelay control transistors 11, 12 in accordance with the voltages thatappear at the two terminals NO1, NO2 of the operating switch 14. Thecontroller 61 further controls automatic opening and closing, performscontrol to prevent an object from becoming caught in a power window andcontrols remote operation, as set forth above. Provided within a controlunit 60 are the controller 61 and a submersion sensing transistor 62,which are molded in plastic. The base of the transistor 62 is connectedto the open terminal 28. In addition to the above-mentioned terminals24, 25, 28, 26, 27, the control unit 60 is also provided with terminals63, 64 for connecting the terminals NO1, NO2 of the operating switch 14to the control unit 60.

A power-supply voltage E4 is being applied to the emitter of transistor62. If a state is attained that is equivalent to one in which the openterminal 28 is connected to ground via a leakage resistance owing tosubmersion, the transistor 62 turns on. A voltage substantially equal tothe voltage E4 is input to the controller 61.

The controller 61 is programmed so as to execute the malfunctionprevention processing described below. If voltage input from thetransistor 62 exceeds a threshold voltage, the controller 61 judges thatsubmersion has been detected. If the voltage at the terminal mb of motor1 that enters from the terminal 25 is the power-supply voltage E1 or avoltage in the vicinity thereof, the controller 61 judges that the motor1 is rotating in the reverse direction and outputs a control signal (Hlevel) that is for turning on the transistor 11. As a result, the relaycoil 2 a is energized and therefore the terminal ma of motor 1 alsoattains the power-supply voltage E1, whereby rotation of the motor 1 isstopped.

An arrangement in which the controller 61 is made to execute thefollowing malfunction prevention processing may be adopted. When thecontroller 61 judges that that submersion has been detected based uponan input signal from the transistor 62 and judges that the motor 1 isbeing rotated in the forward direction by the voltage at the terminal maof motor 1 input from the terminal 24, the controller outputs a controlsignal, which is for turning on the transistor 12, thereby actuating therelay 3.

The shorting circuit is provided in this embodiment as well. The switch31 of the shorting circuit operates in association with the operatingswitch 14 in such a manner that when the operating switch 14 isconnected to the terminal NO1, the common terminal C of the switch 31 isconnected to the normally open contact NO. As a result, when the relay 2is actuated in an attempt to rotate the motor 1 in the forward direction(to open the window), the ends of the relay coil 3 a are shorted and therelay 3 is restored.

FIG. 5 illustrates a modification. Here a control unit 70 has twoadditional functions in comparison with the control unit 60 shown inFIG. 4.

One function is obtained by adding on the malfunction preventioncircuitry (transistors 22 and 23) shown in the first embodiment (FIG.1). As a result, even if the above-described malfunction preventionprocessing function of controller 61 becomes inoperative, it is possibleto prevent a malfunction in which the motor is rotated in the reversedirection owing to submersion.

The other function is to rotate the motor 1 in the forward direction,without the intervention of the controller 61, in operative associationwith a forward-rotation operation by the operating switch 14. Thevoltage of a power supply E5 is applied to the emitter of a transistor71 via a terminal 76. The base of the transistor 71 is connected to theterminal NO1 of the operating switch 14 via a terminal 77 and a diode75. The collector of the transistor 71 is connected to the emitter ofthe transistor 22 via a diode 72.

If the operating switch 14 is connected to the terminal NO1, the base ofthe transistor 71 is connected to ground and the transistor 71,therefore, turns on. If submersion is sensed, the transistor 22 turns on(even if the voltage E1 is not being applied to the terminal 25) and sodoes the transistor 23, whereby the relay 2 is actuated. Even if themotor 1 is not rotating in the reverse direction, and even if thecontroller 61 is malfunctioning when submersion occurs, the motor 1 canbe rotated in the forward direction by manipulating the operating switch14. It should be noted that the diodes 72, 73, 74, 75 are for preventingreverse current.

In this modification, the pull-up resistors 15, 16 are molded inside thecontrol unit 70. Thus, what circuits and elements are included insidethe control unit (mold) can be changed depending upon designconsiderations.

In any case, in the foregoing embodiment, the shorting circuit causesthe relay coil of a relay that rotates the motor in the reversedirection to be shorted in operative association with operation of anoperating switch in a direction that rotates the motor forwardly.However, instead of this arrangement, or in addition thereto, a shortingcircuit may be provided for shorting a relay coil that rotates the motorin the forward direction in operative association with operation of theoperating switch in a direction that rotates the motor reversely.

What is claimed is:
 1. A motor drive apparatus for driving a motor in aforward direction or in a reverse direction by actuating a relay thatrotates the motor in the forward direction or a relay that rotates themotor in the reverse direction by supplying power to the motor inresponse to a forward-rotation command or reverse-rotation commandprovided by an operating portion, comprising: submersion sensing meansfor sensing that at least the operating portion of the motor driveapparatus has become submersed; first malfunction sensing means forsensing that one relay of said relays, which is for rotating the motorin a predetermined one direction, has been actuated; and first forciblecontrol means for actuating the other relay in response to submersionbeing sensed by said submersion sensing means and actuation of the onerelay being sensed by said first malfunction sensing means.
 2. A motordrive apparatus according to claim 1, further comprising: secondmalfunction sensing means for sensing that the other relay has beenactuated; and second forcible control means for actuating said one relayin response to submersion being sensed by said submersion sensing meansand actuation of said other relay being sensed by said secondmalfunction sensing means.
 3. A motor drive apparatus according to claim1, wherein said motor is a motor for driving an opening and closing bodyof a vehicle.
 4. A motor drive apparatus according to claim 3, whereinrotation of said motor in one direction is rotation in a direction thatcloses said opening and closing body, and rotation of the motor in theother direction is rotation in a direction that opens said opening andclosing body.
 5. A motor drive apparatus according to claim 1, furthercomprising a shorting circuit for establishing a short circuit across arelay coil of the relay that rotates the motor in said one direction, inoperative association with manipulation of said operating portion so asto generate a command that rotates the motor in said other direction. 6.A motor drive apparatus having two relays for rotating a motor in aforward or reverse direction by supplying power to the motor, whereinthe relays are actuated to rotate the motor in the forward or reversedirection in accordance with the operating state of an operating portionthat is for commanding forward or reverse rotation of the motor,comprising: submersion malfunction sensing means for outputting asubmersion malfunction detection signal upon sensing that the motordrive apparatus has been submersed and that one relay of the saidrelays, which is for rotating the motor in one direction, has beenactuated; and forcible control means for energizing a relay coil that isfor actuating the other of the said relays, irrespective of theoperating state of said operating portion, in response to output of saidsubmersion malfunction detection signal.
 7. A motor drive apparatushaving two relays for rotating a motor in a forward or reverse directionby supplying power to the motor, wherein the relays are actuated torotate the motor in the forward or reverse direction in accordance withthe operating state of an operating portion that is for commandingforward or reverse rotation of the motor, comprising: submersion sensingmeans for outputting a submersion detection signal upon sensing that themotor drive apparatus has become submersed; and forcible control meansfor actuating both of said relays, irrespective of the operating stateof said operating portion, in response to output of said submersiondetection signal.
 8. A motor drive apparatus according to claim 6,wherein said motor is a motor for driving an opening and closing body ofa vehicle.
 9. A motor drive apparatus according to claim 8, whereinrotation of said motor in one direction is rotation in a direction thatcloses said opening and closing body, and rotation of the motor in theother direction is rotation in a direction that opens said opening andclosing body.
 10. A motor drive apparatus according to claim 6, furthercomprising a shorting circuit for establishing a short circuit across arelay coil of the relay that rotates the motor in said one direction, inoperative association with a shift of said operating portion to a statein which a command that rotates the motor in said other direction isgenerated.